<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button id="count">点我</button>
    <div id="show"></div>
    <script>
        var a = (function(){
            var count = 0
            var button = document.getElementById('count')
            button.onclick = function(){
                Event.trigger('add',count++)
            }
        })() 
        var b = (function(){
            var div = document.getElementById('show')
            Event.listen('add',function(count){
                div.innerHTML = count
            })
        })
    </script>
</body>
</html>